JPH05275172A - Light emitting device and manufacturing method thereof - Google Patents

Abstract

(57) Abstract (Modified) Objective To disclose an improved light emitting device comprising an image display array comprising a plurality of light emitting pixels arranged in intersecting rows and columns. [Structure] Each pixel is arranged on a common electrically insulating light transmissive substrate 101. The pixels in each row contain and are joined by a common light transmissive first electrode element disposed on the substrate. The first electrode elements in adjacent rows are laterally spaced on the substrate. The organic electroluminescent medium 103 is arranged on a supporting surface formed by the first electrode element and the substrate 101. The pixels in each column contain and are joined by a common second electrode element arranged on the organic electroluminescent medium 103. The second electrode element in the adjacent row is on the organic electroluminescent medium 1
03 are arranged at intervals in the lateral direction. Walls that are taller than the thickness of the organic electroluminescent medium 103 are located along a common boundary of pixels in adjacent columns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent image display device and a manufacturing method thereof.

[0002]

2. Description of the Prior Art European Patent No. 349,265 of Scozzafava (patent application issued by the European Patent Office on January 3, 1990) discloses an organic electroluminescent image display device and a method for manufacturing the same.

Scozzafava discloses a substrate having a series of laterally spaced anode strips of indium tin oxide in parallel. An organic electroluminescent medium is overlaid on the anode strip. Parallel cathode strips, oriented orthogonally to the anode strip and laterally spaced apart, are formed on the organic electroluminescent medium by patterning after depositing the cathode-forming metal as a continuous layer. Is formed in. Patterning the cathode layer into cathode strips has been done by spin coating a solution of monomeric negative working photoresist in 2-ethoxyethanol. The photoresist is imagewise exposed to UV radiation to create a cross-linked pattern, and the non-cross-linked photoresist is placed in the array 2
Remove by soaking in ethoxyethanol for 2-3 seconds. This removes the unirradiated photoresist, exposing the areas of the cathode layer. This exposed area of the cathode layer is removed by dipping the array in an acidic etching bath consisting of a 1000: 1 water: sulfuric acid solution. After making the cathode strips by this procedure, the array is rinsed with water and spun to remove excess water.

[0004]

An organic electroluminescent device constructed of an anode and a cathode, each of which is an integral element, which emits light in response to an applied voltage and stops emitting when the applied voltage is removed. Although the device can open and close the switch, it lacks image display performance when used alone. Electrodes overlaid on an organic electroluminescent medium when providing image display performance to the organic electroluminescent device by patterning each of the anode and cathode into relatively vertically oriented parallel strips. The problem arises that the element has to be patterned after its application. When this is done by conventional wet chemical patterning techniques, especially those exemplified by Scozzafava, either or both of the performance of the image display and the effective operating life are
Degraded over similar organic electroluminescent devices with integrated cathode and anode. Degradation of both the organic electroluminescent medium and the cathode has been observed.

[0005]

SUMMARY OF THE INVENTION In one aspect, the invention relates to a light emitting device comprising an image display array of a plurality of light emitting pixels arranged in intersecting rows and columns. Each pixel is disposed on a common electrically insulating light transmissive substrate, and the pixels in each row contain a common light transmissive first electrode element disposed on the substrate, and It is joined by it. The first electrode elements in adjacent rows are laterally spaced on the substrate. An organic electroluminescent medium is arranged on a supporting surface formed by the substrate and the first electrode element. The pixels in each column contain and are joined by a common second electrode element disposed on the organic electroluminescent medium, and the second electrode elements in adjacent columns are organic electroluminescent. Spaced laterally on the medium.

The light-emitting device is characterized in that walls having a height which exceeds the thickness of the organic electroluminescent medium are arranged along a common border of pixels in adjacent columns. The wall is sandwiched between the organic electroluminescent medium and the supporting surface, and the second electrode element is
Laterally from one wall at one boundary and from a second wall at another, in each row overlying the organic electroluminescent medium and separating two adjacent rows It is extended to the position where it is arranged at intervals.

Another aspect comprises an image display array comprising a plurality of light emitting pixels arranged in intersecting rows and columns, each pixel arranged on a common electrically insulating light transmissive substrate. The pixels in each row contain and are joined by a common light transmissive first electrode element disposed on the substrate, the first electrode elements in adjacent rows being laterally on the substrate. Spaced apart, the organic electroluminescent medium is disposed on a supporting surface formed by the substrate and the first electrode element, and the pixels in each column are disposed on the organic electroluminescent medium. A second light-emitting device that contains a common second electrode element and is joined by the element, and the second electrode elements in adjacent rows are laterally spaced on the organic electroluminescent medium. apparatus In the manufacturing method, (a) a step of providing a substrate with first electrode elements arranged in rows laterally spaced on the surface to form a supporting surface, and (b) forming an organic electroluminescent medium on the supporting surface. It relates to a method for manufacturing a light emitting device, which comprises the steps of attaching and (c) forming a second electrode element on the surface of the organic electroluminescent medium.

The method of the present invention forms a series of walls having a height that exceeds the thickness of the organic electroluminescent medium at the common boundaries of pixels in adjacent columns prior to depositing the organic electroluminescent medium. It is characterized in that A source for vapor deposition of the metal forming the second electrode element is oriented at an angle with respect to the support surface that sandwiches each wall between the source and an adjacent portion of the organic electroluminescent medium surface, and The metal forming the second electrode element is selectively deposited on regions of the organic electroluminescent medium surface other than the regions where the walls are sandwiched between the source and the organic electroluminescent medium surface.

An advantage of the present invention is that the organic electroluminescent device of the invention having image display performance exhibits operating characteristics comparable to comparable organic electroluminescent devices except that it does not have image display performance. The point is that you can.

The method of the present invention for making an organic electroluminescent device for image display offers the advantage that the electrodes overlying the electroluminescent medium can be first deposited in their desired pattern. To do. Therefore, the procedure of removing the metal to form the desired pattern of the overlaid electrodes and the drawbacks associated with such a procedure are completely eliminated.

Embodiments In some cases, the acronym EL is used instead of the term "electroluminescent". It should be noted that the device dimensions, such as layer thickness, are often in the sub-micrometer range, so the scale of the drawing sacrifices dimensional accuracy for clarity.

Referring to FIGS. 1 and 2, there is shown an organic EL light emitting device 100 capable of forming an image display. Light transmission having a series of light-transmissive, preferably transparent, first electrode elements C1, C2, C3, C4 and C5 arranged on a substrate in laterally spaced parallel rows. An electrically insulating, preferably transparent, electrically insulating substrate 101 is shown. The organic EL medium 103 is in contact with and overlaid on the entire first electrode element except the leftmost part. Above this organic EL medium is a series of second electrode elements R1, R2, R3, R4 arranged in rows arranged in parallel laterally spaced.
And R5 are overlaid. The second electrode element is an organic EL
It extends laterally beyond the lower edge of the medium (shown in FIG. 1) and onto the lower portion of the substrate.

A conventional image display device can have a very large number of electrodes in columns and rows, but the 6 by 6 electrodes shown are sufficient to explain the operating principle of the device. 6
With 6 rows of electrode elements, the EL device can emit light independently in any or all of the 36 individual areas (hereinafter referred to as pixels or imaging pixels). A pixel is a region P completely defined by a dashed line or a dashed line and one or two edges of the EL medium.
1 to P36 are shown in FIG. The pixels together form an image display array.

In operation, a particular emission pattern from the device that is visible by looking at the substrate 105 is created. In a preferred mode of operation, one row of pixels is excited in succession at a time, with a rate chosen such that the time interval between repeated excitations of each row is below the detection limit of the human eye, typically less than 1 / 60th of a second. The device is excited to emit light by repeating the excitation of the array at. To the observer, despite the fact that the device only emits from one row at any one time,
The image formed by the emission from all excited columns is visible.

To create the desired image pattern, the electrode elements C1 to C6 are independently biased to form portions of the appropriate image pattern in the pixels P1 to P6 sharing the common second electrode element R1. For example, it is desired to emit light from the pixels P1, P2, and P3, and at the same time, P4, P5, and P6
If light emission from the is not desired, electrode elements C1, C2
And C3 are electrically biased to the electrode element R1 to excite light emission, while the electrode elements C4, C5 and C are excited.
No 6 has no bias to excite the emission, or it is electrically biased opposite to the emission.
Immediately after exciting the pixels P1 to P6 in the first column with a desired pattern, a new pattern of excitation is generated on the electrode elements C1 to C6.
, And then biasing the electrode element R2,
The light emission of the specific pattern from the pixels P7 to P12 in the second column is excited.

An important point to note is that for the light emitted by the EL medium, it must pass through one of the first electrode elements. To be light transmissive, the thickness of each first electrode element must be limited, which also increases its resistance. By choosing the row and column arrangement shown, the first electrode element is required to carry as little current as necessary to excite one pixel. The second electrode element need not be light transmissive, so it can be thicker and have a lower resistance, each providing the total current required to excite all pixels in any one column. It can be conducted.

A significant advantage of the present EL device 100 over similar prior art devices capable of forming an image display is that the EL medium or EL medium can be formed in the desired patterning of the second electrode elements to form columns. The point is that neither of the second electrode elements deteriorates at all. The second electrode element is deposited in the desired pattern on the EL medium rather than being uniformly deposited and then patterned as taught by Scozzafava cited above. It is not necessary to contact any processing material (eg, solution) with the EL medium or with the material forming the second electrode element to create the desired electrode array pattern. This is made possible by providing the device with features defining the column pattern of the second electrode elements to be deposited prior to depositing the EL medium.

The first step of forming the organic EL device 100 is a step of providing a light-transmissive, preferably transparent, conductive layer on the surface of a light-transmissive, preferably transparent substrate.
It is most common to choose a glass substrate coated with indium tin oxide. Subsequent to photoresist patterning, the substrate is provided with the first electrode elements C1-C6 by etching the unprotected areas of indium tin oxide with hydroiodic acid and then removing and rinsing the photoresist. Indium tin oxide,
Instead of using tin oxide or a similar transparent conductive oxide, fabricate the first electrode element with a light transmissive thin layer of any metal with a high (eg, higher than 4.0 eV) work function. be able to. A mixture of chromium and gold is specifically contemplated for making the first electrode element.

The substrate may be formed of any conventional light transmissive electrically insulating material, and the first electrode may be formed of relatively stable light transmissive metals and metal oxides. The substrate and the first electrode element together provide an attachment surface 107 that can withstand conventional chemical patterning techniques such as photolithography without degradation.

The element responsible for defining the desired row pattern of second electrode elements to be deposited on the EL medium is the wall 10.
It is 9. This wall may be formed on attachment surface 107 by any convenient conventional patterning technique.

In a simple and particularly preferred technique, the walls are formed by spin coating a negative working photoresist on the attachment surface. If desired, the spin coating process can be repeated after drying to increase the photoresist layer thickness. The patterned exposure allows the photoresist in the exposed areas to crosslink and become insoluble while the unexposed areas are removed by development and cleaning techniques. Crosslinking by exposure is strong,
Creates a relatively hard wall.

Many alternative wall forming techniques are possible. Instead of building a thick photoresist layer by a continuous spin coating process, a thicker photoresist layer is formed on the substrate by laminating a photoresist surface on a soft support such as a transparent film to the support surface. be able to. In this embodiment, the photoresist is typically a monomer that polymerizes upon imagewise exposure after lamination. Stripping the film after imagewise exposure also removes the monomer in the unexposed areas.

In another wall forming technique, the photoresist does not form a wall, but is present in the region of the support surface surrounding the wall to define the pattern of the wall. The formation of the photoresist layer can take any of the above aspects, but the imagewise exposure is chosen to leave the photoresist in the area surrounding the wall. Either positive or negative working photoresist may be used. Subsequently, a wall forming material such as silica, silicon nitride, alumina, etc. is uniformly deposited so as to overlap the existing photoresist, and is also deposited on the deposition surface in the wall region.
After the wall is formed, the photoresist can be removed by any convenient conventional technique, such as solvent lift-off.

In order to deposit the second electrode elements in a desired column pattern, the organic EL device is fabricated with walls arranged along the common boundaries of pixels in adjacent columns. Then
The organic EL medium is deposited on the walls and the remaining attachment surface by any convenient conventional vapor deposition technique. As shown in FIG. 1, since the left and lower edges of the attachment surface do not include the organic EL medium, the electrode element portions extending into these areas are used to connect external electrical leads. be able to. Such laterally extending electrode element portions are commonly referred to as bonding pads. A mask, such as a piece of tape, along the edge of the substrate near the bond pad site can be used to define the deposition pattern of the organic EL medium. Alternatively, the organic EL medium can be mechanically removed by polishing after it has been deposited over the deposition surface.

Generally, any vapor deposition technique known to be useful for depositing one or more layers of organic EL media may be employed. It is generally preferred to choose the wall height to exceed the thickness of the organic EL medium. In an efficient device structure, the organic EL medium is 1 μm (10,000 angstroms) even when present in multilayer form.
A thickness of less than, and typically half this thickness is indicated.
Thus, achieving a useful wall height is well within the capabilities of conventional patterning techniques useful for wall formation.

After depositing the organic EL medium, a source of metal used to deposit the second electrode element is provided. For efficient organic EL devices, the second electrode element requires a metal exhibiting a lower (<4.0 eV) work function to contact the organic EL medium. Depositing one or more low work function metals, alone or in combination with one or more higher work function metals, onto organic EL media by any conventional directional (line in the figure) transport technique. You can In order to ensure linear transport from the source to the organic EL medium surface, the metal atoms are preferably transported under reduced pressure. This increases the mean free path of the metal ions during transport from the source to the organic EL medium surface, thus minimizing scattering and maintaining the attachment in a directional controlled manner. Generally, the distance between the source and the surface of the organic EL medium is smaller than the mean free path of the metal atoms (that is, smaller than the average moving distance until the metal atoms collide with the atoms in the ambient atmosphere). Lower the ambient atmospheric pressure during the deposition process. Conventional deposition techniques that meet the requirements of directional transport include vacuum evaporation, electron beam deposition, ion beam deposition, laser ablation and sputtering.

As shown in FIGS. 1 and 2, each wall adjoins the source and the surface of the organic EL medium in order to achieve the deposition pattern of the second electrode elements in laterally spaced rows. The attachment surface 107 is arranged with respect to the metal source to be attached so as to be sandwiched between the portions. When the deposition is performed in such an orientation, the sandwiched wall portion blocks the metal ions flying from the source, and thus prevents the metal from being deposited on the organic EL medium on one side of the wall. This provides a space between adjacent rows of second electrode elements. The practically preferred orientation range for the source of the metal atom is such that the angle between the flying direction of the metal atom and the normal to the attachment surface (axis perpendicular to the attachment surface) is about 10 to 60 degrees, preferably about 15 to 45 degrees. Established in some cases.

Depositing a low (<4.0 eV) work function metal, alone or in combination with one or more high work function metals, deposits a continuous layer containing a low work function metal to form an organic EL medium. It only requires maximizing the efficiency of electron injection into. However, as shown, the second electrode element is responsible for carrying the current generated by all the pixels in each column and is therefore expected to provide a continuous layer.
It is preferred to increase the thickness of the second electrode element beyond the thickness level of 00-500 Angstroms. It is possible to form thick electrodes of up to 1 μm or more with the initial metal composition, but with a relatively high work function (thus lower chemical reactivity) after initial formation of a continuous layer containing a low work function metal. It is generally preferred to modify the composition so that only the metal of For example, to reduce the resistance of the second electrode element by depositing a convenient high work function metal commonly used in circuit fabrication, such as gold, silver, copper and / or aluminum, magnesium (preferred low Work function metal) and silver,
It would be preferable to increase the thickness of the initial continuous layer of indium or aluminum. The combination of a low work function metal at the interface of the organic EL medium with a high work function metal that completes the thickness of the overlying second electrode element is particularly advantageous. Because, even if the low work function metal is limited to the interface of the second electrode element with the organic EL medium, the high electron injection efficiency produced by the low work function metal is sufficiently realized, and at the same time, the presence of the high work function metal exists. Is to improve the stability of the second electrode element. Thus, a combination of high injection efficiency and high electrode element stability is achieved with this arrangement.

FIG. 3 shows an alternative structure for the first electrode element. The features of substrate 101 and all other devices are the same as those described above in connection with device 100, except as noted. The requirement that the first electrode element be light transmissive limits the thickness of the electrode element and thus sets an upper limit for its electrical conductivity. In order to increase the electrical conductivity of the first electrode element without reducing the light transmissivity, as shown, the current conducting strip 3 need not be light transmissive.
The light transmissive portion 301 with the edges 03 in contact is used to form the first electrode elements C5 'and C6'. To increase the electrical conductivity of the current-conducting strip over that of the light-transmissive portion, the strip is most conveniently formed by depositing a metal in the indicated area above the first electrode element of the type described above. Let The metal can be more conductive than the material forming the light transmissive portion of the first electrode element. Since the current conducting strips need not be light transmissive, it is preferable to increase their electrical conductivity further by making them thicker than the light transmissive portions of the first electrode elements. Each current-conducting strip extends across the entire width of each first electrode element in each bonding pad area 305. This structural modification of the first electrode element can be used to increase the light emission, reduce the internal resistance, or both.

FIG. 4 shows the details of an alternative image display organic EL device structure which is the same as the details of the previously described device, except as otherwise noted. A significant structural improvement is the thin electrically insulating strip (or pedestal) 4
01 is a point formed on the attachment surface 107 before forming each wall 409. Since the pedestal is insulative, the wall is not in electrical contact with the first electrode element and therefore may be constructed from any conventional conductive, semiconducting or insulating material. If the walls are made of a conductor such as metal, they can facilitate the current conduction of the second electrode element. Note the increased likelihood of direct contact between each wall and the overlying second electrode element at the upper corner of the wall. Because
This is because the large radius of curvature of the organic EL medium in this arrangement increases the likelihood of discontinuity or thinning in these areas. In the landing pad area, not shown, the organic EL medium is completely absent, and the second electrode element and the wall are in direct contact in each case.

The possibility of inadvertent thinning or discontinuity of the organic EL medium increases in regions of small radius of curvature, so
An important function of the insulating pedestal is to reduce the risk of inadvertent short circuit between the first electrode element and the second electrode element in the area immediately adjacent to the wall. The pedestal can take the form of any relatively thin insulating layer such as evaporated silica or an organic insulating layer. The pedestal can be of any convenient thickness, but is generally preferred to be thinner than the organic EL medium.

FIG. 5 shows the details of an alternative image display organic EL device structure which is the same as the device of FIG. 4 above except as otherwise noted. In this embodiment, the wall is electrically conductive. The organic EL medium 503 differs from the organic EL medium 103 in that the adhering surface of the organic EL medium 503 is inclined with respect to the source for supplying the material for adhering the organic EL medium, and the medium is adhered. Again, the organic EL medium does not adhere to one side of each wall, as part of each wall is sandwiched between the source and the adhesion surface. The preferred angular and directional deposition considerations described above for the deposition of the second electrode element are applicable here for the deposition of organic EL media. It is preferred that the organic EL medium is directionally attached by vacuum evaporation.

After the organic EL medium 503 has been deposited, the second electrode element is redeposited as previously described. However, the orientation of the attachment surface with respect to the metal source in forming the second electrode element is selected so that the second electrode element attaches to the side of each wall without the organic EL medium. This results in direct contact between the second electrode element and the conductive wall. In this arrangement, the electrically insulating pedestal not only prevents the conductive wall from shorting the first and second electrode elements, but also allows the second electrode element to directly contact the first electrode element in areas where the organic EL medium is not present. It is also important to prevent contact.

One of the distinct advantages of the present invention is that the organic EL medium and the second electrode element can be formed continuously in the same vacuum chamber and contained in intermediate handling or ambient air, especially ambient air. The point is that there is no exposure to moisture. The ambient air to which the second electrode element and the organic EL medium are exposed is very limited, as the device can be encapsulated or placed directly in the housing immediately after the second electrode element is deposited. ..

It will be appreciated that the organic EL medium and the second electrode element may be further protected from the environment prior to removal from the vacuum chamber to which they are attached. For example, after forming the second electrode element, an electrically insulating layer such as silica is uniformly deposited on the second electrode element and the upper surface of the organic EL medium, and then
The finished product can be removed from the vacuum deposition chamber.

An alternative specifically contemplated alternative for protecting the second electrode element and the underlying organic EL medium prior to removal from the vacuum chamber is to deposit a protective capping layer over the second electrode element. .. In its simplest form, the capping layer is simply a higher work function metal than the underlying second electrode element, as described above. If the capping layer itself is conductive, it is applied by the same techniques described above to form the second electrode element. Depositing on the second electrode element not only protects the second electrode element, but also the entire active area of the organic EL medium. Note that the only area of the organic EL medium that is active in emitting light is the area under the second electrode element. The organic EL medium in the area separating the adjacent second electrode elements is not an active emitter and in any case occupies only a small part of the total pixel array area. Nevertheless, if desired, a uniform insulating layer such as silica can be applied after the application of the capping layer. Thus, when the image display array is removed from the vacuum chamber, it is well protected and does not need to be immediately installed in a sealed housing to avoid degradation of device characteristics. All of the moisture sensitive parts of the device can be formed and protected during the manufacturing process in a single vacuum chamber without premature exposure to ambient air.

In the discussion above, the walls are shown schematically in vertical cross section. Conventional wall-forming techniques, such as the photoresist patterns routinely used in semiconductor fabrication, can provide walls with substantially vertical cross-sections as shown.
However, it is recognized that conventional patterning techniques are known and suitable for use in wall fabrication that allows for alternating wall cross-sectional shapes. For example, the top edge of the wall in many patterning procedures is somewhat rounded. Development and etching techniques are known that are capable of undercutting the wall, i.e. making the bottom thickness of the wall less than the thickness near the top edge of the wall. Similarly, the sides of the wall can be sloped so that the bottom of the wall is wider than near the top edge of the wall. In order to adapt to the above-mentioned orientation limitation of 60 degrees, it is preferable that the angle between the side surface of the wall and the normal to the attachment surface is less than 60 degrees (most preferably less than 45 degrees).

The number and size of the individual pixels can be selected within the conventional range that satisfies known imaging applications. Pixels with smaller edge length require more care in construction. One edge for fine image formation
Pixels with edge lengths in the range of 400-20 μm are contemplated.
For the vast majority of imaging applications, one edge is 100 μm
For applications where pixel edge lengths above are accepted and where more stringent image sharpness is required, one edge may be 25
Pixel edge lengths of μm and above are common.

A photoresist layer up to a thickness of about 20 μm is formed,
It can be manufactured by a single spin coating process. By using the lamination or multiple spin coating technique, a photoresist layer with a thickness of 200 μm or more can be easily obtained. Since the thickness of the organic EL medium rarely exceeds 1 μm, it is clear that it is easily realized to obtain a wall whose height exceeds the thickness of the organic EL medium. In the fabrication of pixels with an edge length of 400 μm or less, it takes about
Walls with heights in the range of 0.5-10 μm are usually preferred.

For pixels with a relatively short edge length, the wall height to width ratio is important. This is because walls account for a greater proportion of the total pixel area in such applications. A wall height to width ratio range of 5: 1 to 1: 1 is readily realized and is generally preferred. The active portion (ie, the light emitting portion) of each imaging pixel is at least the entire area.
It is intended to make up 25%, and optimally at least 50%. For pixels with an edge larger than about 400 μm, the wall width rarely occupies a significant portion of the total pixel area.

The discussion above has optionally described exemplary materials for constructing image-displaying organic EL devices. From the above, a wide variety of conventional materials useful in the practice of the present invention are believed to be apparent and, thus, are well known for patterning and / or imaging materials, developers, etchants, substrates, conductors, electrical insulators, etc. I do not intend to enumerate.

The material of the image display organic EL device of the present invention is
It can take any of the forms of conventional organic EL devices,
For example, Scozzafava, cited above; Tang U.S. Pat. Nos. 4,356,429; 4,539,507; 4,720,4.
No. 32; No. 4,885, 211; No. 4,769,292; No. 4,9
No. 50,950; US Patent Application No. 557,8 filed on July 26, 1990
No. 47 (currently patented); US Patent Application No. 5,047,6
87; US Patent Application No. 557,857 (now patented) by Scozzafava et al. Filed on July 26, 1990; July 26, 1990.
US Patent Application No. 557,285 (currently patented) to Van Slyke et al., Currently filed; US Patent Application No. 561,552 (currently patented) to Van Slyke et al., Filed July 26, 1990. Reference is made to these disclosures herein.

As will be apparent from these disclosures, the organic EL medium is preferably constructed from a hole injection and transport zone. The organic EL medium is preferably further formed from a hole injection layer adjacent to the device anode and hole transport layer, and an electron injection and transport zone. The electron injection and transport zone is preferably constructed from an electron injection layer adjacent the cathode of the device and a light emitting layer where recombination of holes and electrons occurs. The preferred device structure for the first electrode element is to form the anode of the device, and the preferred device structure for the second electrode element is to form the cathode of the device. The cathode can, if desired, be protected by another new layer, which is not illustrated or described here, but is described in detail in the cited reference.

[0044]

The invention can be further appreciated by reference to the following specific embodiments.

Example 1 Fabrication of Wall on Substrate A wall was fabricated on a substrate by photolithography using the following steps. 1) Application of negative working photoresist onto a substrate; the substrate was a clean circular glass wafer with a diameter of 10.2 cm. The composition of the negative working photoresist used was as follows: 65 g of chlorobenzene as solvent, 1 g of ketocoumarin as sensitizer, 2 g of ethyl 4-dimethylaminobenzoate as activator, dipentaerythriotal monohydroxyl pentaacrylate. (Sold by Sartomer under the trade name SR-399)
20 g, poly (methyl methacrylate) polymer (DuPo
It is commercially available from nt under the trade name Elvacite 2021). Approximately 3-5 ml of photoresist was deposited on the wafer and spun at low speed of 400 revolutions per second (RPM) for 5 seconds to spread the photoresist over the substrate surface. The rotation speed was then rapidly increased and spun at 2000 RPM for 60 seconds. The wafer substrate with the spin coated photoresist was then dried at 135 ° C for 60 seconds in an air convection oven.

2) Photomask Exposure of Photoresist The photomask consisted of a chromium pattern on a 161.3 cm ² square glass substrate. Chrome pattern
It had a set of parallel lines of various line widths and line pitches. Line pitch between centers is 100 μm, line width is
It was set to 10 or 20 μm. The length of these lines was 5 cm. Photoresist exposure was performed on the mask aligner using a near UV light source.

3) Development of Photoresist The pattern-exposed photoresist was developed using xylene as a solvent. This was done by spinning the substrate at 400 RPM for 40 seconds while spraying xylene onto the substrate. 4000 R for developed photoresist pattern
After rotating with PM for 30 seconds, it was baked and dried in a convection oven for 60 seconds.

The height of the wall made of the above procedure, made of cross-linked photoresist, was 12 μm ± 1 μm. The wall width was either 10 or 20 μm and the center-to-center pitch was 100 μm. It has been found that the wall height is easily modified by changing the spin speed at which the photoresist is spin-coated, or by changing the solids content of the photoresist formulation, or both. ..

Example 2: Gold using a vertical shadow mask
Fabrication of metal electrode A glass wafer having a photoresist pattern fabricated according to Example 1 was transferred to a vacuum deposition chamber. The wafer was placed at a distance of about 36 cm from a tungsten boat containing silver as an evaporator source. The orientation of the wafer was such that the angle between the normal between the center of the wafer and the boat source and the normal of the wafer was 35 degrees. An aperture mask was placed in contact with the wafer to define the entire area where silver was to be deposited. Adhesion of silver is about 1 x 10
The vacuum chamber pressure was ^-6 torr. The thickness of the silver film deposited on the wafer surface was about 2000 angstroms.

Conductive silver lines were produced between adjacent walls on a glass wafer by the vapor deposition method described above.
Examination by optical microscopy revealed that the parallel silver lines were separated from each other by a well-defined gap formed by the interleaved walls between the adjacent portion of the substrate and the silver source of the vaporizer. Electrical measurements have shown that these conductive parallel lines are completely separated from each other. The electrical resistance of any adjacent silver line was higher than 1 × 10 ¹² ohms.

Example 3 A wall was made on a glass wafer by the method described in Examples 1 and 2, except that the height of the wall was varied by adjusting the rotation speed when applying the photoresist to the wafer. Let The wall thickness was 6.2 μm and 9.0 μm. Silver lines were deposited on these patterns as described in Example 2 at a deposition angle of 35 degrees. Resistance measurements showed that the resistance between adjacent silver lines was higher than 1 × 10 ¹² ohms.

Example 4 Instead of silver, a magnesium: silver alloy (element ratio 1
A 0: 1) line pattern was prepared as described in Examples 1 and 2. The height of the wall was 6 μm. The attachment angle is
It was 20 degrees. Optical inspection showed a clear gap between the Mg: Ag lines and resistance measurements showed complete electrical isolation between adjacent lines.

Example 5 A 2.4 μm wall was prepared according to Example 1. A Mg: Ag alloy line was attached at an angle of 30 degrees. All Mg: Ag lines were completely electrically isolated. When the deposition angle was reduced to 0 degrees (ie, the deposition was perpendicular to the substrate surface) almost all the lines were electrically connected.

This example illustrates that electrical isolation between metal lines was easily achieved using low profile walls and low sloped deposition angles. Conductivity between lines was observed without the use of oblique attachment angles.

Example 6: Preparation of organic EL medium matrix
Work 58 cm ² square glass substrate with indium tin oxide (IT
O) patterning the coating (thickness 0.18 μm),
A set of parallel lines having a line pitch of 380 μm and a line width of 280 μm was formed. Parallel walls having a height of 1.6 μm were manufactured by the method described in Example 1 at right angles to these ITO lines. 200 μm pitch between adjacent walls
And the wall width was 20 μm.

An organic electroluminescent media matrix was deposited on top of the glass substrate surface with ITO lines and photoresist. The organic EL medium matrix consists of a copper phthalocyanine layer (200 Å), 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl layer (1400 Å) and an aluminum trisoxine layer (1000 Å) in this order. ). These layers were produced by vacuum evaporation. The deposition rate was 2-5 Å / sec for each of the three organic layers, and the deposition angle was 0 degrees for each of the three organic layers. On the organic EL medium,
A Mg: Ag (10: 1) alloy film was deposited through the opening. The adhesion angle was 45 degrees. This deposition produced electrically isolated Mg: Ag lines on the organic EL media matrix. Individual pixels were illuminated by applying a bias of about 10-15 volts between a particular ITO line and a particular Mg: Ag line.

[0057]

An advantageous feature of at least one embodiment of the organic electroluminescent device of the present invention is that the device having image display performance is an organic electroluminescent device which does not have image display performance but is otherwise equivalent. It is capable of exhibiting operating characteristics comparable to the device.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an organic electroluminescent device capable of displaying an image.

2 is a cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is a plan view showing details of an alternative structure that meets the requirements of the invention.

FIG. 4 is a cross-sectional view showing details of an alternative structure that meets the requirements of the invention.

FIG. 5 is a cross-sectional view showing details of an alternative structure that meets the requirements of the invention.

[Explanation of symbols]

 100 ... Organic electroluminescent light-emitting device 101 ... Substrate 103, 503 ... Organic electroluminescent medium 107 ... Adhesive surface 109, 409, 509 ... Wall 301 ... Light transmissive part 303 ... Current conducting strip 305 ... Bonding pad area 401, 501 … Insulating strips (or pedestals)

Claims (3)

[Claims] 1. A light emitting device comprising an image display array comprising a plurality of light emitting pixels arranged in intersecting rows and columns, each pixel being on a common electrically insulating light transmissive substrate. Are arranged; the pixels in each row contain and are joined by a common light-transmissive first electrode element arranged on the substrate; the first electrode elements in adjacent rows are on the substrate Laterally spaced apart; an organic electroluminescent medium is disposed on a support surface formed by the first electrode element and the substrate; the pixels in each column are organic electroluminescent. Containing and joined by a common second electrode element disposed on the medium; the second electrode elements in adjacent rows are laterally spaced on the organic electroluminescent medium. Are; Walls that are taller than the thickness of the organic electroluminescent medium are located along a common boundary of pixels in adjacent columns; the wall is between the organic electroluminescent medium and the support surface. And a second electrode overlying the organic electroluminescent medium in each row, and in one row separating two adjacent rows from one wall at one boundary, A light emitting device extending to a laterally spaced position from a second wall at another boundary; 2. A light emitting device comprising an image display array comprising a plurality of light emitting pixels arranged in intersecting rows and columns; each pixel being on a common electrically insulating light transmissive substrate. Are arranged; the pixels in each row contain and are joined by a common light-transmissive anode arranged on the substrate; the anodes in adjacent rows are laterally spaced on the substrate The substrate and the anode together form a support surface; laterally spaced walls exhibiting a height greater than 1 μm are disposed on the support surface, Each wall overlies each of the anodes, the walls being arranged along the boundaries of pixels in adjacent columns; an organic electroluminescent medium exhibiting a thickness of less than 1 μm is provided on the support surface and above it. Placed on a wall that overlaps The pixels in each column contain and are joined by a common cathode disposed on the organic electroluminescent medium; and the cathode is in each column separating two adjacent columns. A light emitting device extending from one wall at one boundary to a position laterally spaced from a second wall at another boundary. 3. A light emitting device comprising an image display array comprising a plurality of light emitting pixels arranged in intersecting rows and columns, each pixel on a common electrically insulating light transmissive substrate. The pixels in each row contain and are joined by a common light transmissive first electrode element disposed on the substrate; the first electrode elements in adjacent rows are on the substrate. Laterally spaced; an organic electroluminescent medium is disposed on a support surface formed by the first electrode element and the substrate; each row of pixels is on the organic electroluminescent medium. Containing and joined by a common second electrode element arranged in a row; and second electrode elements in adjacent rows are laterally spaced on the organic electroluminescent medium. From the above In the method of manufacturing an optical device, the following steps; a step of providing a substrate with first electrode elements arranged in rows laterally spaced on the surface to form a supporting surface; an organic electroluminescence device on the supporting surface. Depositing a centrifuge medium; forming a second electrode element on the surface of the organic electroluminescent medium; connecting a series of walls having a height greater than the thickness of the organic electroluminescent medium to the pixels in adjacent columns. Forming a common boundary prior to depositing the organic electroluminescent medium; a source for vapor deposition of the metal forming the second electrode element, relative to the support surface,
Orienting each wall at an angle interposing between the source and an adjacent portion of the organic electroluminescent medium surface; and on the organic electroluminescent medium surface between the source and the organic electroluminescent medium surface. And a step of selectively adhering a metal forming the second electrode element to a region other than the region where the wall is sandwiched.